Electric glow-lamp.



P. BLAU.

ELECTRIC GLOW LAMP. APPLICATION FILED APLI?, 1906.

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FRITZ BLAU, or BERLIN, GERMANY, AssIGNCR, BY MEsNE ASSIGNMENTS, To GENERAL ELECTRIC COMPANY, A CORPORATION or NEW YORK.

' ELECTRIC GLOW-LAMP.

To all whom it may concern.'

Be it known that I, Dr. FRITZ BLAU, chemist, a subject of the Emperor of 4Austria-Hungary., and a resident of Alte Jakobstrasse 139, Berlin, Germany, have invented certain new and useful improvements in Electric Glow-Lamps; and I do hereby declare the following to be a full, clear, and exact description of the invention, such'as will enable others skilled in the art to which ity appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specilication.

My invention relates to improvements in electric glow lamps.

in a recent form of electric glow lamp in whichy the illumination is produced by the incandescence of a metallic body, it has been found necessary tov provide the laments with Suspenders. The experiments made in this direction, however, have failed lto give favorable results, especially in the case of incandescence bodies consisting of a material that cannot be drawn into wire for example osmium lamps. These lamps cannot be used in all positions without the laments buckling to a very considerable degreewith a consequent risk of short-circuit ing. An additional defect also consists in the liability of the filaments to adhere to the Suspenders, which leads to the rupture thereof when exposed to changes of temperature such as occur when switching the electric current on or ofi'.

The present invention relates to an electric glow lamp the metallic incandescence filaments of which are held fast by suspenders, outside of or independently`of the f circuit, in such a manner that the changes in dimension produced by the above mentioned changes of temperature; are rendered harmless. The chief defect to which such metallic filaments are exposed, and which consists in the filaments fracturing in consequence of the temporary contraction occurring at each cooling, and also the permanent contracting which occurs as the incandesoence period is prolonged, and the danger of short Circuiting caused by the buckling of the heated filaments, are if not entirely obviated, at least reduced to a minimum. IThe :means employed tp effect this purpose con- Speciication of Letters Patent. Application filed April 17, 1906. Serial No. 312,123.

sist in making the 'suspender exceedingly elastic. Several ways of carrying out the invention are shown in the accompanying drawings, in which- Figure l illustrates in elevation a glo lamp adapted for use in any position. Fig. 2 is a similar view f a glow lamp,- adapted for use in a depending position. Figs. 3 and i respectively illustrate to a larger scale the method ofsuspending the filament and the two positionsof a suspender mounted on the ends ofthe holder, with the current on and off.

The form of lamp which I have illustrated comprises the bulb e having at its base a stem through which the leading-n wires are sealed. This stem carries a central holder Z having hubs formed thereon nearthe'stem and at the end remote' -from the stem. for the arms or Suspenders which support the filament. ln the present case the arms which support the portion of the filament near the stem also serves as part ofthe electrical circuit of the filament loops.

The metal filament a (Fig. 1) is preferably bentat a sharp angle to form the point of suspension (which can be easily done by loading the depending filament when white hot) and is hung at that point on a suspender b constructed of thin wire of some metal that is very elastic and very'refractory for example tantalum to form a spring. The suspender may advantageously be made by twisting two or more wires together. It may alsobe composed of other materials, dsuch as very hard glass (quartz glass).

The suspender b terminates in a hook, for the reception of the incandescence filament and is'mounted in a socket c (Figs. 3 and 1l) of platinum or other suitable material that has been previouslyl fused into the central holder'cl. The filament is suspended from the hook by first bending down the socket so as to depress the suspender b, then laying the filament in the hook of the suspender and afterward raising lthe socket again so as to exert a pull to impart sufficient tension to the suspender b and filament (Fig. 4). A lamp of this kind can be used in any position.

lf the lamp is intended for use in an inverted position, that is, if the filaments hang Patented 0610.151914.

These hubs serve as anchorages downward, as in Fig. 2,' the end of the suspender is bent into an eye through which the filament passes. In this case if the lilaments should fuse on or adhere to the suspenders the elasticity of the latter would prevent the rupture of the filaments When the current was switched olf, which rupture vwould probably occur in lamps having rigid Suspenders.

It should be mentioned that there is no necessity for the spring Suspenders to be fixed in the sockets or for the spring portion and hook to bev of the same material, as a hook or other fastening device for receiving the filament can be attached to the spring, which fasteningv device will, preferab'liy, be made of refractory material (Fig. 3).

' o improve the heat conducting property of the hooks and prevent them from opening, which might permit of the filaments slipping ofi', .they may be provided with a small quantity of putty-like substance, as indicated iii Fig. 3. For this purpose, I may employthe graphite and carani'el cement I which is commonly used to secure filaments of'incandescent lamps.

The behavior of the spring suspender is shown in Fig. 4, the full line showing the position of the spring when under the tension due to contraction ofAthe filament on turning 01T the current, while the dotted line shows the position it will assume when the current is turned on and the lilament relaxed. f

The dimensions of the spring suspender which are most suitable are determined by the elasticity, softness and weight of the filaments, and also of the elasticity of the Suspenders themselves. Foi` example in the case of osmium or tungsten filaments, yof pointed horseshoe shape (Fig. l) measuring -80 millimeters in height (the total length of the filament being therefore 14C-160 mm.) and weighing about 6 milligrams, a spring to be suitable should visibly bend when the hook, which is about 11 millimeters away from the point of attachment of the spring, is exposed to a pull of 10-20 milligrams, without its limitof elasticity being approximately reached, whereas a pull of f6 gram would strain the spring beyond the limit of elasticity and cause permanent flexion. The filament in vturn will readily and permanently support a load of gram when white hot, but this load never occurs in practice. In the foregoing example the spring "was stretched or put under tension to such an extent that when lthe filament was out the `hook moved a distance of about 2 millimeters.

A glow lamp of this kind actsin the following manner when in use. On switching onA the current, the filament expands. The elastic Suspenders therefore relax in a visible manner, and return to their original posicounteract that produced by the distortion.

I claim:

l. The combination with a lamp stem and a central holder carried thereby, of a plurality of metallic filament loops mounted adjacent and substantially parallel with said holder and having their ends -fastened to supports projecting perpendicularly from said holder near the stem, and straight uniformly elastic and refractory wires rigidly attached to and projecting perpendicularly from the end of said holder remote from the stem with their outer ends bent into hooks for engaging with the bends of said filament loops, said wires being flexible with respect to the supports so as to yield resiliently and longitudinally of said holder upon expansion and contraction of said filament loops.

2. The combination with a lamp stem and a central holder carried thereby, of a plurality of metallic filament loops mounted about said holder withtheir ends secured to rigid supports projecting from said holder near the stems and forming part of the electrical circuit of said loops, and straight uniformly resilient supports extraneous to the circuit rigidly attached to and projecting perpendicularly from the other end of said holder and engaging at their outer ends the bends of said loops, said resilient supports being yieldingly movable relative to said rigid supports by theexpansion and contraction of said loops.

3. The combination with supporting means comprising a lamp stem and a central holder carried thereby, of a plurality of metallic lilamentloops arranged adjacent said holder and having their ends fastened to supports projecting from said holder near the stem and springs of refractory material projecting from the end of said holder remote from fthe stem and engaging the bends of said loops.

4.. The combination with supporting means comprising a lamp stem, a central holder carried thereby and supports projecting from said holder near the stem, of a plurality of filament loops arranged adjacent said holder and havin their ends fastened to said supports, and5r springs projecting from the end Aof said holder remote from the stem and engaging the bends of said loops.

5. The combination with supportin means comprising a lamp lstem and a centra holder carried thereby, of a plurality of metallic filament loops arranged adjacent said holder,

.- the end of said holder remote from the stem Witnesses:

arms projecting roin saidl holder `.near said". In testimony, that I claim the foregoing stem and. supporting the portions,` of said as my invention, I have signed my name in filament loops adjacent said stem, and represence of two subscribing witnesses. silient arms projecting perpendiculerlj)7 from IDR. FRITZ BLAU.

with their outer ends bent into hooks for en- WOLDEMAR HAUPT, gaging the bends of said loops. vHENRY HASPER. 

